SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bff58b39c7df1607497a9eed56f2d581e9712f39a241c3f096ec5608fec58edc' 
  AND token = 'VIQiZwk2YNFdW8bZYx4KaYIwjjkQe5SjwadVQ8qx8w8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}